Impacts of land use on Indian mangrove forest carbon stocks: Implications for conservation and management

Abstract

Globally, mangrove forests represents only 0.7% of world's tropical forested area but are highly threatened due to susceptibility to climate change, sea level rise, and increasing pressures from human population growth in coastal regions. Our study was carried out in the Bhitarkanika Conservation Area (BCA), the second-largest mangrove area in eastern India. We assessed total ecosystem carbon (C) stocks at four land use types representing varying degree of disturbances. Ranked in order of increasing impacts, these sites included dense mangrove forests, scrub mangroves, restored/planted mangroves, and abandoned aquaculture ponds. These impacts include both natural and/or anthropogenic disturbances causing stress, degradation, and destruction of mangroves. Mean vegetation C stocks (including both above- and belowground pools; mean ± standard error) in aquaculture, planted, scrub, and dense mangroves were 0, 7 ± 4, 65 ± 11 and 100 ± 11 Mg C/ha, respectively. Average soil C pools for aquaculture, planted, scrub, and dense mangroves were 61 ± 8, 92 ± 20, 177 ± 14, and 134 ± 17 Mg C/ha, respectively. Mangrove soils constituted largest fraction of total ecosystem C stocks at all sampled sites (aquaculture [100%], planted [90%], scrub [72%], and dense mangrove [57%]). Within BCA, the four studied land use types covered an area of ~167 km and the total ecosystem C stocks were 0.07 Tg C for aquaculture (~12 km ), 0.25 Tg C for planted/ restored mangrove (~24 km ), 2.29 teragrams (Tg) Tg C for scrub (~93 km ), and 0.89 Tg C for dense mangroves (~38 km ). Although BCA is protected under Indian wildlife protection and conservation laws, ~150 000 people inhabit this area and are directly or indirectly dependent on mangrove resources for sustenance. Estimates of C stocks of Bhitarkanika mangroves and recognition of their role as a C repository could provide an additional reason to support conservation and restoration of Bhitarkanika mangroves. Harvesting or destructive exploitation of mangroves by local communities for economic gains can potentially be minimized by enabling these communities to avail themselves of carbon offset/conservation payments under approved climate change mitigation strategies and actions.

Effect of the conversion of mangroves into shrimp farms on carbon stock in the sediment along the southern Red Sea coast, Saudi Arabia

“…SOC in mangrove areas is likely a result of A. marina, mainly due to litter fall and underground roots instead, in the shrimp farm, the vegetal cover has been eliminated. Other studies on the variation of SOC content in mangrove areas due to changes in land use coincide with the present finding by always indicating a significant decrease in SOC content in the transformed areas (Andreetta et al, 2016;Arifanti et al, 2019;Bhomia et al, 2016;Cameron et al, 2019;Gevana et al, 2015;Kauffman et al, 2018;Kauffman et al, 2016;Pérez et al, 2017). The decline in the amount of organic matter in the shrimp farms has been attributed to decomposition of the organic matter in soils especially during periods when the ponds were drained after shrimp harvests.…”

Effects of permeable barriers on total ecosystem carbon stocks of mangrove forests and abandoned ponds in Demak District, Central Java, Indonesia

“…A variety of soil management techniques in coastal areas have resulted in changes in soil properties that also affect soil C storage ability (Bhomia et al 2016). Where conversion of mangrove forests into aquaculture ponds regularly changes the biophysical soil that plays a role in controlling soil C, previous study has reported that conversion of mangroves into shrimp ponds caused a reduction in TECS from 1023 ± 87 Mg C ha −1 to 499 ± 56 Mg C ha −1 in Mahakam Delta (Arifanti et al 2019).…”

Biomass and vegetation carbon stock in mangrove forests of the Andaman Islands, India

“…Indian mangroves host 46 true mangrove species, which represent about 56% of global mangroves species (Ragavan et al, 2016). Despite considerable work on the floristics and ecology, the inventory of carbon stocks in mangrove habitats of the Indian coast are scanty, and currently, only a few studies have reported the carbon stocks of these systems in Mainland India (Kathiresan et al, 2013(Kathiresan et al, , 2014Ray et al, 2013;Mitra & Gatti, 2015;Bhomia et al, 2016;Sahu et al, 2016;Suresh et al, 2017;Vinod et al, 2018;Gnanamoorthy et al, 2019;Banerjee et al, 2020;Harishma et al, 2020). Mangroves of the Andaman and Nicobar Islands (A & N Islands) are among the best in terms of density and growth in the country (Dagar et al, 1991;Mandal & Naskar, 2008;Ragavan et al, 2019) and accounts for an area of 616 km 2 ; out of which, 614 km 2 is in Andaman Islands with just 2 km 2 spread in Nicobar Islands (FSI, 2019).…”